Traditionally, fabric conditioning has been carried out either during the rinsing step of a fabric washing and rinsing process or during tumble drying of the fabric. Typically, rinse conditioning is accomplished by adding a liquid dispersion of a rinse conditioning agent to the rinse liquor. The liquid dispersion was traditionally distributed and made available to consumers as a ready to use aqueous dispersion. More recently, concern for the environment and consumer convenience has led to the sale of concentrated aqueous dispersions which are either used in smaller amounts or are mixed with water to form a dilute composition before use.
In EP 234082 it has been proposed to supply rinse conditioner as a solid block. This approach requires the use of a special restraint for the block and may also require the modification of the washing machine to enable the block to be dissolved and dispensed by a spray system.
Various proposals have been made to supply fabric softener in granular or powdered form.
WO-A2-02/44310 relates to a granular conditioning compound. There is no disclosure of the particle size of the cationic softening material.
WO-A1-99/60081 discloses stabilised compositions comprising quaternary ammonium materials. There is no mention of mean particle size of the softening material.
WO-A1-94/07978 describes a process for producing powdered or granular detergent mixtures. No reference is made to particle size.
EP-A1-0739976 discloses textile and hair conditioners comprising esterqauats and fatty acid amides. There is no mention of esterqauats having a specific mean particle size.
JP622875 discloses specific quaternary ammonium materials which show better softening effects than di(hydrogenated tallow alkyl) dimethyl ammonium chloride.
EP 111074 discloses a powdered rinse conditioner based on a silica carrier for the softening agent. A disadvantage of using a carrier such as silica is that it can cause bulking of the product and appears to serve no function beyond making the powder compatible with other ingredients that may be contained in washing powder.
WO 92/18593 describes a granular fabric softening composition comprising a nonionic fabric softener and a single long alkyl chain cationic material. The specification teaches that effective cationic softening compositions when used in granular form exhibit poor dispersion properties and so, despite the obvious environmental and transport saving advantages of selling a water free powdered rinse conditioner, manufacturers have not done so.
EP-B1-0568297 discloses a powdered rinse conditioner comprising a water insoluble cationic active and a nonionic dispersing agent.
It is known that solid fabric conditioners can be formed by combining quaternary ammonium compounds with a water soluble carrier such as urea.
U.S. Pat. No. 5,259,964 (Colgate-Palmolive) discloses a free flowing spray-dried rinse conditioner. U.S. Pat. No. 4,427,558 (Unilever) discloses a method of preparing fabric softening particles comprising a cationic fabric conditioning materials urea and a salt of a fatty acid.
A problem with powdered rinse conditioners Is that they are frequently difficult to disperse in water and thereby subsequent softening of fabrics is detrimentally affected.
Deposition aids have been proposed for depositing clay softeners. For example, WO-A1-00/60039 (Proctor and Gamble) discloses a solid rinse conditioner comprising clay, surfactant, a solid carrier and a flocculating agent which aids deposition of the clay. The preferred flocculating agent is an organic polymer such as polyethylene oxide.
EP-A-0107479 (Unilever) discloses a liquid or granular rinse conditioner comprising a nonionic conditioner (such as sorbitan monostearate) and aluminum chloro-hydrate which acts as a deposition aid for the nonionic conditioner.
EP-A-0267999 (Unilever) discloses a liquid or powder rinse conditioner comprising a non-cationic softener and a nonionic cellulose ether derivative as a deposition aid for the softener.
JP 06306769 (Kao) discloses a solid fabric softener comprising a tertiary amine, a quaternary ammonium salt and urea or a water soluble inorganic salt.
JP 62057639 (Lion) discloses the production of cationic surfactant granules in which a dialkyl quaternary ammonium powder is granulated with an alkali metal chloride or an alkaline earth metal chloride. The chloride is present to improve softness.
JP 02182972 (Kao) discloses a solid softening agent comprising a dialkyl quaternary ammonium salt, a monoalkyl quaternary ammonium salt and urea or a urea derivative. The composition may also contain a water soluble inorganic salt such as sodium chloride, sodium sulphate, magnesium sulphate and potassium nitrate.
Surprisingly, it has now been found that a solid rinse conditioning composition comprising a particular cationic softening agent and a carrier, such as urea, disperses particularly well in liquids. It has also been found that such compositions impart excellent softness to fabrics.